Tillerson could face a rocky confirmation process, given concerns among both Democrats and Republicans about his ties to Russia. If Tillerson can overcome the skepticism of Republicans, he could win confirmation since their party will control a slim majority in the Senate when Trump takes office on Jan. 20.

Democrats’ misgivings about Tillerson go well beyond the worry that he might be too accommodating toward Moscow. They see risks of conflicts if the head of the $380 billion oil giant becomes the nation’s top diplomat and they want to ensure that his personal wealth and business interests get close scrutiny.

Aides said Democrats began assembling experts to prepare for Tillerson’s confirmation even before his nomination was formally announced on Tuesday.

“We will bring in people who have been through confirmation battles before,” a Democratic leadership aide said. “We want to have a very thorough review. We are very comfortable with this process taking as long as it needs.”

In many ways, Exxon operates its own kind of diplomatic corps, dispatching executives to network with government officials in the more than 40 countries in which the company operates.

“The scale and the reach of Exxon Mobil ... does raise some questions about those relationships and how his experience at the helm of Exxon Mobil will influence his decision-making as secretary,” said Democratic Senator Chris Coons, a member of the Senate Foreign Relations Committee, which will hold Tillerson’s confirmation hearing next month.

Tillerson, 64, is on the New York Times’ list of the 200 highest-paid CEOs, having earned some $24.3 million in 2016. He has a net worth of $150 million, plus a $70 million pension plan. He would likely need to divest his holdings of Exxon stock.

RUSSIA TIES

Democrats are also consulting with foreign affairs experts as they examine his relationships with countries such as Russia.

Tillerson opposed sanctions imposed on Russia after its annexation of Crimea. He has said they are often ineffective. Exxon has said the sanctions on Russia could cost it hundreds of millions of dollars or more.

“We are looking at issues like, will he need to recuse himself from decisions on sanctions?” another Democratic aide said.

Exxon has also come under attack for the financial arrangements of its oil production in Chad, where the company’s lawyers are negotiating over a $74 billion fine tied to accusations of royalty underpayment.

Exxon also has development rights in Iraq, which is battling Islamic State, and Saudi Arabia, with its controversial record on human rights and complex relationship with U.S. ally Israel and Iran, whose international nuclear agreement signed by President Barack Obama has been harshly criticized by Trump.

“Mr. Tillerson has demonstrated he knows the corporate world and can put his shareholders’ interests first, but can he be a respected secretary of state that puts the national security interests of the American people first?” asked Senator Ben Cardin, the ranking Foreign Relations committee Democrat.

Tillerson enjoys strong support from Republican leaders, but some party members offered more muted reactions.

Marco Rubio, a Republican member of the Foreign Relations panel, who ran against Trump for the Republican presidential nomination, said he had “serious concerns” about Tillerson’s nomination.

Even critics said, however, they were open to the appointment, if Tillerson gives satisfactory answers during the confirmation process.

“There are lots of ways that energy and our energy dependence has influenced our foreign policy over decades, and hopefully he will bring some insights as a result of that experience,” Coons said.

“It is not all bad that he’s got 40 years of experience globally in business,” he added. (Additional reporting by Ernest Scheyder and Liz Hampton in Houston; Editing by Caren Bohan and Peter Cooney)